Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2436c Report Date: 09-May-96:17:07 Version: ********** Check-in Date: ********** 1.Proposal Title: THE STARBURST GALAXY NGC 5102 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO Sub Category NEARBY GALAXIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Prof. Kenneth C Freeman MT STROMLO & SIDING SPRING O AUSTRALIA 61-62-490264 PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract NGC 5102 is a nearby (4 Mpc) galaxy of classical SO appearance which has undergone a recent starburst in its nucleus, bulge and disk. Because it is so close, it provides a unique opportunity to investigate the IMF of a typical starburst, the mass of starburst matter relative to the underlying older population, and the effect of the starburst on the largescale structure of this galaxy. PC images will be used to derive the luminosity function and IMF for the starburst matter in two regions of NGC 5102, at different distances from the nucleus. In the inner high surface brightness region, the crucial massive end of the mass function (stars more massive than 8 Ms) is accessible. In the outer disk, where the surface brighness is lower, we will be able to derive the mass function for stars more massive than 5 Ms. This proposal is part of a larger program on this important galaxy, involving extensive ground based optical and radio observations. The HST is required for its high spatial resolution, which enables faint stars of the starburst to be detected against the high background surface brightness of this galaxy. ------------------------------------------------------------------------------------ 8. Scientific Key Words: GALAXIES, STARBURST, LUMINOSITY FUNCTION, MASS FUNCTION ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.40 par: 0 10. Num targs pri: 3 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2436c PI: Prof. Kenneth C Freeman Proposal Title: THE STARBURST GALAXY NGC 5102 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Colin A Norman STSCI USA Prof. Kenneth C Freeman MT STROMLO & SIDING SPRING AUSTRALIA OBSERVATORIES Dr. Nicholas Z Scoville CALTECH USA Dr. Peter J Quinn MT STROMLO & SIDING SPRING AUSTRALIA OBSERVATORIES ------------------------------------------------------------------------------------ 3. Description of proposed observations. The observations will be made with the PC, because its field size is well suited to the program and its adequate sampling of the image profile is required. We will use the wideband filters F439W and F569W, because they will provide satisfactory transformations to the standard BV system and they give the best signal to noise ratio for observations of our blue stars against the redder diffuse background of this galaxy. The first field is centered about 35 arcsec from the nucleus, along the major axis, towards the SW, for the purpose of deriving the luminosity function in the bulge region. The proposed exposures in the two filters will give a S/N ratio larger than 4.0 for early type stars with V = 26 near the nucleus, and correspondingly fainter at larger distances. The exposures will be split into two or three parts, to minimize blooming from foreground stars and to allow discrimination of the fainter cosmic ray events. The second field is centered at about 100 arcsec from the nucleus, in the same direction; this field covers the transition region between the bulge and the disk. The field centers have been adjusted to minimize the number of stars in each field that are bright enough to cause blooming, and the field area affected by blooming will be negligible. We have also chosen a field outside the galaxy, to be observed in an identical way to the first two fields, in order to derive the local Galactic background luminosity function accurately . ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HST is required for this program, because its high spatial resolution allows photometry of faint stars against the background surface brightness distribution of this galaxy. From the ground, such photometry is so limited that our program would be impossible. For example, in the disk of NGC 5102, where the surface brightness is about 21.2 B mag per square arcsec, the limiting magnitude from the ground is about B = 24.5, and only a very restricted portion of the upper end of the mass function would be observable (about 16 to 40 Ms). However, the innermost parts of NGC 5102 are particularly important, because of the likely connection of starbursts and bulge formation and in these regions ground based work is impossible. For example, at about 5 arcsec from the nucleus, the background surface brightness is about 18.5 B mag per square arcsec, and the faintest stars that could be detected under the best groundbased conditions have B = 22. (We recall that the brightest stars that have been detected in the disk of NGC 5102 have B = 22). We have started an extensive program of groundbased optical CCD imaging and spectroscopy to investigate the structure and kinematics of the young and older populations in NGC 5102 and the chemical properties of the resolved HII regions. We are also involved with CO single dish and interferometer observations of NGC 5102, and will undertake HI synthesis observations with the Australia Telescope in about one year. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Our primary aim is to derive the mass function in NGC 5102, over a range of distances from the nucleus. Two fields in NGC 5102 are a bare minimum, plus a field away from the galaxy for estimating the Galactic background luminosity function. The problem is to measure magnitudes and colors of faint blue stars against the redder diffuse background of NGC 5102. We have estimated S/N ratios for the wide band filters and find that F439W and F569W are the best for this purpose. In the disk of NGC 5102, a 3000 sec exposure gives a S/N ratio larger than 3 for a star with V = 27; we can then estimate the mass function over the mass range 5 to 40 Ms. In the inner regions, where the surface brightness is higher, a 3000 sec exposure gives a S/N ratio of 4 for a star with V = 26. The corresponding mass range is then 8 to 40 Ms. While this range is more restricted than in the outer regions, it will give us the important bright end of the mass function. To obtain a significantly larger mass range in the inner regions of NGC 5102 would require very much longer exposures. Each exposure should be split into 1500 sec parts, to reduce problems with cosmic rays and blooming. Two such exposures is the minimum number for this purpose. Spacecraft time was estimated from the formulae given in the instructions for use of the RPSS Resource Estimator, with 325 min total exposure time, 87 min overheads and 40 min acquisition time. The total estimated unocculted spacecraft time is 452 min and the efficiency is 72%. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Not applicable. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Point spread function fitting codes will be used to derive instrumental color magnitude diagrams for the resolved stars in each field. Ground based observations of the comparison field will be used to transform the instrumental F439W, F569W system to the standard B,V system. At this stage, we do not know whether crowding of resolved images will be a problem; in any case, we will estimate the completeness as a function of magnitude and background surface brightness by the usual procedure of randomly inserting artificial stars into the data. We can then subtract the comparison field color magnitude distribution from those of the corrected galaxy fields to derive uncontaminated galaxy field samples.Theoretical color magnitude distributions, convolved with the observational errors, will then be fitted to the galaxy field samples to derive the mass functions, using estimates of metallicity derived from ground based spectroscopy of the HII regions. In the outer parts of NGC 5102, we will resolve the brightest stars of the underlying old population. However, these will not contaminate our starburst sample, because our colors will be accurate enough to distinguish old red giants from A stars of the starburst population. We will avoid data near the dustlanes, although the extreme weakness of the dustlanes suggests that internal reddening is negligible. Further analysis will address the questions discussed in the scientific justification, such as the total mass of starburst matter relative to the older population, and the variation of the most recent epoch of star formation with radius. For the gas expulsion physics and the relation of age with kinematics, we will combine results from the PC data with our groundbased observations. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We would be grateful if scheduling could ensure that residual images from previous observations do not contaminate our images. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Not applicable Page 4 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The data analysis capabilities of STScI and Mt Stromlo Observatory (MSO) will be used for data analysis. The hardware and software required is already available and in use at both institutions. Graduate students at JHU and MSO will work on particular aspects of this project. Australian radio and optical facilities (the Australia Telescope, MSO 2.3-m telescope, AAT) will be used for much of the associated ground based observations. ------------------------------------------------------------------------------------ 11. Address Information Name: KENNETH C FREEMAN Category: PI Institution: MT. STROMLO AND SIDING SPRING OBS Address: PRIVATE BAG, WODEN P.O. City: CANBERRA, ACT State: Zip Code: 2606 Country: AUSTRALIA Telephone: 61-62-490264 Telex (or e-mail): AA62270 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 2436c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5102-F1 GALAXY; TYPE=S0; BULGE RA = 13H 19M 05.0S +/- 1", 1950 V = 454 1 V = 26 +/- 0.5, TYPE = B5 V DEC = -36D 22' 32" +/- 1" 2 B = 26 +/- 0.5 3 SURF-BKG(V) = 19.6 +/- 1.0 4 SURF-BKG(B) = 20.2 +/- 1.0 Comments: SURF-BKG +/- VALUES GIVE RANGE OF SURF- BKG WITHIN PC FOV. ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5102-F2 GALAXY; TYPE=S0; DISK RA = 13H 19M 01.3S +/- 1", 1950 V = 454 1 V = 26 +/- 0.5, TYPE = B5 V DEC = -36D 23' 20" +/- 1" 2 B = 26 +/- 0.5 3 SURF-BKG(V) = 21.5 +/- 0.5 4 SURF-BKG(B) = 22.1 +/- 0.5 Comments: SURF-BKG +/- VALUES GIVE RANGE OF SURF- BKG WITHIN PC FOV. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC5102-F3 GALAXY; TYPE=S0; RA = 13H 19M 32.7S +/- 1", 1950 V = 454 1 V = 26 +/- 0.5 BACKGROUND DEC = -36D 21' 37" +/- 1" 2 B = 26 +/- 0.5 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2436c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5102-F1 PC IMAGE ALL F439W PRE-FLASH=YES 3 25M 7 2 1 POS TARG +0.0,+0.0 CLOCKS=YES 75M 4 / 1-6 CR-SPLIT=NO GROUP 1-2 NO GAP Comments: S_TO_N ESTIMATE USED SURF-BKG VALUE AT CENTER OF PC FOV. ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5102-F1 PC IMAGE ALL F569W PURGE=YES 1 50M 10 1 1 SAME ORIENT FOR 2 PRE-FLASH=YES 3 AS 1 CLOCKS=YES Comments: S_TO_N ESTIMATE USED SURF-BKG VALUE AT CENTER OF PC FOV. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC5102-F2 PC IMAGE ALL F439W PRE-FLASH=YES 1 50M 7 2 1 GROUP 3-4 NO GAP CLOCKS=YES 4 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC5102-F2 PC IMAGE ALL F569W PURGE=YES 1 50M 15 1 1 SAME ORIENT FOR 4 PRE-FLASH=YES 3 AS 3 CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC5102-F3 PC IMAGE ALL F439W PRE-FLASH=YES 1 50M 7 2 1 GROUP 5-6 NO GAP CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC5102-F3 PC IMAGE ALL F569W PRE-FLASH=YES 1 50M 15 1 1 SAME ORIENT FOR 6 CLOCKS=YES AS 5 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2436c [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PRE-FLASH=YES CLOCKS=YES CR-SPLIT=NO PURGE=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.40 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category NEARBY GALAXIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG +0.0,+0.0 / 1-6; GROUP 1-2 NO GAP SAME ORIENT FOR 2 AS 1 GROUP 3-4 NO GAP SAME ORIENT FOR 4 AS 3 GROUP 5-6 NO GAP SAME ORIENT FOR 6 AS 5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F439W F569W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5102-F1 NGC5102-F2 NGC5102-F3 ------------------------------------------------------------------------------------------------------------------------------------